speedbit.com claims to have 110 million users of DAP world wide and is one of the popular and best download manager for windows. One of its biggest strength to download big files in a faster connection at optimum speed is, it can automatically search for best mirrors and download different parts of the file form multiple location.

BUT Download Accelerator Plus(DAP) may switch its download to a un trusted or malicious website while searching for fastest mirrors for a particular file under certain conditions. If the ACTUAL, trusted host providing the file is DOWN or due to network congestions the users may get and execute a malicious file instead.

I've included two screenshots which should be self explanatory. Check out the url?s in each screenshot and see from where the file is being received at the end.

In the screenshot I'm trying to download 'Windows 2003 sp1' from download.microsoft.com but DAP automatically chooses to download it only from ftp.planet.nl as my network was having tooooooooo low internet bandwidth at that time.

Further more, on some network/OS there might be rules for MAX CONNECTION PER HOST and (say)if in the network someone is already downloading some file from download.microsoft.com the outcome will surely be a VIRTUAL network congensation for download.microsoft.com within that DMZ.

For my test I used another client computer behind the gateway to send continuous ping ( 17 different instants) to download.microsoft.com As a result, for my network download.microsoft.com was off the radar. So, in my another computer DAP chooses to download Win2003 sp1 from ftp.planet.nl instead. So, even after my network gained its full throttle... no-wounder DAP was still downloading the file from ftp.planet.nl

My test network setup was a 3 computer PC which was left on default configuration with Winxp sp2 (patchlevel: latest)

Changes: This advisory is slightly modified than the one that I emailed to the vendor about a week back and tried contacting it, but with no response till now!

Result: I was receiving the file from an unknown and un-trusted source which could be infected with a malicious program.

BUT fyi: I haven't researched on HOW and WHERE 'DAP' queries to get other possible mirrors for the particular file.

Conclusion: I insist NOT to use download managers that does the same while downloading important files. Or either force your download manager and check whether the file is being downloaded from the original URL or not.